I'm curious if you agree with the following statement.
While investigating a Problem, you know that someting is going wrong, you dig deeper and find out the cause to be something else is going wrong etcetera.

My statement: you have reached the root cause first if you know what IS wrong; as long as you just know what IS GOING wrong, even at a very low level, you have not reached the root cause yet.

You just have to keep asking WHY until you get to a Root cause which will help you take steps to prevent it happening again

Why did the server crash?
Because there was an operating system failure
Why was there an OS failure?
Because an engineer installed an update yesterday
Why did the update cause the OS failure?
Because it was not installed correctly
Why was it not installed correctly?
Because there was no process for installing updates
Why was there no process for installing updates?
Because one has never been created

Root cause is the fact there is no documented process for installing server updates

Solution - Create a documented process for installing updates

This is a very generic example and every situation is different.

You could go back as far as you like with asking WHY, such as 'If the engineer wasn't born then this never would have happened' but that is not sensible and will not achieve anything

Finding the root cause is no good unless you can use it to prevent the issue happening again.

You can't prevent the engineer being born because it's too late but you can create a documented procedure for him to follow when installing updates on servers

Why did the server crash?
Because there was an operating system failure
Why was there an OS failure?
Because an engineer installed an update yesterday
Why did the update cause the OS failure?
Because it was not installed correctly
Why was it not installed correctly?
Because there was no process for installing updates
Why was there no process for installing updates?
Because one has never been created

....

Thanks for your feedback.
I think the "because it was not installed correctly" is closest to the root cause.

I see it as a big capital V where your problem investigation is at the left handside (going down searching for the root cause), the root cause being at the bottom and searching for a solution at the right hand side (why did it go wrong).

I agree with your statement about finding the root cause being no good, however it should be your point of departure and you go as far as judged feasible to come to a solution or to stop the investigation.

Root cause is a red herring. It is a shame that ITIL ever adopted the phrase. root cause is never the issue. Underlying cause is the issue and there can be more than one. The key is that the cause at a level that is accessible to remedy by your organization._________________"Method goes far to prevent trouble in business: for it makes the task easy, hinders confusion, saves abundance of time, and instructs those that have business depending, both what to do and what to hope."
William Penn 1644-1718